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itniflFlag for Norway asked on

PSU tests OK but when changing to another one, PC boots

My PC stopped working the other day. Couldn't turn it on anymore. There was a green light that turned on, on the motherboard, other then that, nothing. No fans, no beeps, nothing on the display. Tested the PSU with a PSU tester, it tested OK. Every voltage and measurement within its range. Still when changing to a different PSU, everything boots and starts as normal. Any known possible explanations to this?

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8/22/2022 - Mon

Check whether your monitor is attached properly to your display card.
Did your whether processor is attached properly

If any of those were not attached properly, I would get the same result with both PSU's. Both PSU's test fine, but computer does not boot with the old one. Re-tested several times.

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Gary Case

As willcomp noted, this simply means the voltages are okay, but the current capacity of the old PSU has deteriorated to where it can no longer power your system.    I'd simply toss the old power supply.    Just be glad it was such a simple problem :-)
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William Peck

These are pretty much the same answers as I gave earlier when I said (a) a voltmeter does not load a circuit and (b) the problem supply was not able to provide the required current.

... Thinkpads_User

@thinkpads_user - note times on our responses. I was typing when you posted your answer.

when i test a PS, i always apply a load to the different voltage rails : 12 V, 5 V, and 3.3 V
i made a rig of car lamps for 12 V loads, and use resistor chains for the others.

another cause that it does not start, can be bulging or leaking capacitors inside the PS
aften you have to repalce only a couple to get it working again
here's how they look :
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Thanks guys! This is great. i'll just toss the old one and use the new one. I don't want to spend time trying to repair it. I am not familiar with such work, would end up spending more time then interests me, and therefore just opt for the simplest solution :)

@itnifl - Thanks for the update. In this case, replacement is probably the right answer.

.... Thinkpads_User

nearly all bad PS's  i had in have been repaired
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William Peck